Question

Oxidation state of Fe in ${\left[ {Fe\left( {C{N_6}} \right)} \right]^{3 - }}$:

Answer 1

The oxidation state indicates the number of electrons accepted or given away by the atom to make the chemical bond with another atom. The charge of the ligand should be known to determine the oxidation state of the atom in the coordinate compound.

Complete answer:
The oxidation state of the coordinate compound can be calculated in the following way,
${\left[ {Fe\left( {C{N_6}} \right)} \right]^{3 - }}$
Let the oxidation state of Fe is X.
Oxidation state of CN is -1.
So the oxidation number of X is,
X + 6 (- 1) = - 3
X = - 3 + 6
$\therefore$ X = + 3
Here, let X be the charge of metal ions we need to find in the coordinate compound, the charge of the ligand is - 1 by doing the calculations as done above we can find the value of oxidation number of the central metal ion in the coordinate compound. The geometry of the compound is dependent on it. Hence, the value of the oxidation state of Fe is + 3. Here, primary valency is oxidation state and secondary valency in coordination number the number of ligands attached as per Werner’s theory. The value of which is important to decide the shape and hybridization of the coordinate compound. d-d transition is helpful to know the symmetry of the molecule and it can be known by the oxidation state of the metal ion.

Note: We can say that the oxidation state of the metal varies from one coordinate compound to another as we know that the charge of the ligand and number of ligands varies, geometry and symmetry also varies.